Appliance Control Knob Support
An appliance control knob assembly includes an encoder with a rotatable shaft. A control knob is connected to the shaft and is mounted on a protuberance that extends into the control knob and provides a bearing mounting surface. The control knob has a hub portion rotationally supported by a bearing mounted within the protuberance, and which engages the rotatable encoder shaft. The encoder is mounted such that prior to attachment of the hub portion with the encoder shaft, the encoder is allowed a degree of movement to come into alignment with the hub portion.
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The present invention relates to appliance control knob assembly constructions, and particularly to constructions of control knobs for use in laundry appliances, such as automated laundry washing machines and dryers.
Automated laundry appliances (such as laundry washing machines and dryers) typically include an external generally rectangular cabinet, a control panel for controlling the washer/dryer operation, and a hinged lid or door that may be swung open to provide top or front-load access to a rotatable cylindrical wash basin (in the case of a washer). In use of an automated laundry washing machine, after placing a load of laundry in the wash basin, along with a suitable type and quantity of laundry detergent, a wash process is initiated by an operator through interaction with the control knob. Similarly, with a dryer, a wash load drying process is initiated through interaction with a control knob. The control knob provides a user interface through which a user may make selections of cycles and various wash (or dry) control parameters. Controlled operation sequences may be carried out using an electronic controller that may, e.g., be provided as an integral part of the control panel, or mounted separately and suitably connected therewith. Such a controller may comprise one or more suitably programmed microprocessors or application specific integrated circuits (ASICs), operably connected to suitable circuitry, e.g., for driving the wash basin drive motor, actuating operation components (e.g., valves and a pump) to fill the wash basin and drain it, dispense additives, etc. Such operations will be carried out in accordance with commands of the controller, generated on the basis of program control and possibly also signals received from various sensors monitoring various operation-related parameters.
Many current designs for knobs in washer and dryer consoles comprise a knob shell with a concentric knob shaft on the inside that is supported on its outside diameter by either a cone shape that contacts the knob shaft only over a very small area close to the front face of the knob, or a cylindrical shape that holds the knob shaft over a larger area/length of the knob shaft.
The rearward end of the knob shaft often is supported by an encoder on an electronic circuit board. Alternatively, some knobs are supported only by an encoder. These designs can create problems of displacement of the knob from its intended aligned mounting position and friction between the knob shaft and the supporting geometry. Unwanted lateral movement of the knob may result from the gap necessarily provided between the knob shaft and the shaft support geometry to allow low friction rotation of the knob. This lateral movement may result in undesirable loosening of the knob or misalignment in relation to the encoder that may hinder knob operation. It may also provide an undesirable user feel. As that gap is increased, the lateral movement may allow the outermost diameter of the knob to rub on the surrounding console structure, causing more friction and wear. This issue is even more prevalent on designs where the knob is supported by only the encoder, as there is a much higher moment arm for any lateral forces (including gravity) to affect the position of the knob and allow it to rub on the console. Conversely, as the gap between the knob shaft and its support geometry is narrowed to reduce lateral knob movement, friction between the knob shaft and its support geometry may increase.
Axial movement of, or forces on, the knob also may be a problem. As the knob is pushed inward during use, it may frictionally engage against the knob shaft support geometry leading to undesirable increased rotation resistance. Axially directed forces on and/or movement of the knob can also cause damage to the encoder to which the knob shaft is attached. If the knob is pulled outward from the console during use, there also may be increased friction between the knob shaft and its support geometry. Also, there may be increased friction between the knob and the console. Small dimensional variations on any of the interacting parts, which are to be expected in injection molding processes, can have a great impact on any of these three potential issues.
SUMMARY OF SELECTED INVENTIVE ASPECTSIn view of the foregoing, it is an object of the present invention to provide a control knob assembly and method of assembly that avoids the drawbacks of prior control knob support arrangements. To this end, in an aspect, the present invention provides an appliance control knob assembly including an encoder that has a rotatable shaft. A control knob is connected to the rotatable shaft. A control knob mounting protuberance extends into the control knob and provides a bearing mounting surface. A bearing is mounted on the bearing mounting surface. The control knob has a hub portion extending through the bearing and engaging with the same so as to be rotationally supported therein. The hub portion further engages with the rotatable shaft of the encoder. The encoder is mounted within the assembly such that prior to attachment of the hub portion with the encoder shaft, the encoder is allowed a degree of movement. As a result, upon engagement of the hub portion with the encoder shaft, the encoder shaft comes into alignment with the hub portion.
In a further aspect, the invention provides a control knob assembly method. In that method, a bearing is mounted on a bearing mounting surface of a control knob mounting protuberance. A control knob is mounted on the mounting protuberance such that the protuberance extends into the control knob, and a hub portion of the control knob extends through the bearing. An encoder is movably mounted within a support structure of a control panel assembly. The encoder has a rotatable shaft. The hub portion is engaged with the encoder shaft such that the engagement is able to move the encoder within the support structure to thereby center the shaft with the hub portion in the event of a misalignment of the shaft and hub portion.
These and other objects, aspects and features of the present invention will be readily apparent and fully understood from the following detailed description taken in conjunction with the appended drawings.
Referring to
Referring now to
The illustrated control knob 11 is rotatable in order to permit the user to select operation cycle settings and other control parameters, with reference to selections indicated by words, icons, or other indicia that may be arrayed (in printed form or otherwise) on the fascia about the control knob, and/or used in conjunction with LCD display 13.
The assembly featured in
Also, as shown in
As illustrated in
Prior to the engagement of the knob shaft 21 with the encoder shaft 25, the control knob 11 is mounted within a bearing which is mounted within the mound-like, frusto-conical protrusion 17, that may be formed (e.g., injection molded) as part of the front housing 19. The illustrated embodiment employs a ball bearing 15. In a known manner, the bearing 15 has a generally toroidal shape formed by a pair of concentric rings/races with circumferential troughs that face each other to form therebetween a raceway within which a set of balls is rotatably trapped to rotate and orbit, thereby providing a low friction rotatable mount of the inner ring/race within the outer ring/race of the bearing. The rings/races and balls may be made of various materials including either metal or plastic, and may employ a wet or dry lubricant to further reduce friction and facilitate smooth rotational movement.
Ball bearing 15 may be press-fit into a collar formed by a central circular cavity 16 formed within the protrusion 17. This fixes the outer ring of the bearing with respect to the protrusion, while rotationally mounting the inner ring. The central shaft of the knob 21 may then be press-fit into the inner ring of the bearing. This press-fitting arrangement positively establishes the translational position and orientation of the knob relative to the front housing 19. The relative movement afforded by the mount of the encoder 23 within the rear housing 24 allows the encoder shaft to come into alignment with that position. Thus, the misalignment problems associated with prior designs, where the knob position is at least in part dependent on the (non-movable) encoder position. Moreover, the mount can be made much stronger than prior designs that rely on only the encoder shaft for support.
Crush ribs may be used to effect the press-fit of the outer race ring of the ball bearing firmly within the recess of protrusion 17, and also to effect the press-fit of the knob shaft firmly within the inner race ring of the ball bearing so that the only movement of the knob relative to the front housing is rotation within the ball bearing.
As illustrated in
During the assembly, a sub-assembly of the knob 11, bearing 15, and front housing unit 19 may be engaged as a unit with rear housing 24. In this process, encoder shaft 25 engages with and advances into knob shaft 21, coming into alignment therewith due to the float afforded by the mount of the PCB 27. At the same time, PCB 27 becomes fixed in its aligned position by virtue of hold-down features now described.
As illustrated by
As shown in the illustrated embodiment, there may be three spring arms 33, angularly spaced 120 degrees apart from each other around the axis of rotation of knob 11 (when it is mounted on the front housing 19), in order to evenly clamp the PCB 27 into place. Each of the spring arms 33 is symmetrically formed as two arm segments that emanate from two spaced points on the rear side of the front housing. The two segments extend parallel to each other a first equal distance, turn inwardly toward each other forming a pair of shoulders 35, then taper inwardly further until joining together centrally to form a closed loop and a rounded, rearwardly protruded end 37. It is this end that comes into engagement with PCB 27 (as seen in
In the illustrated embodiments, the control panel assembly and components are implemented in a control panel of an automated laundry washing machine. It will be understood, however, that aspects of the invention may be applied to other automatic washing/drying appliances, e.g., dishwashing machines, and to electronic appliances in general.
The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.
Claims
1. An appliance control knob assembly, comprising:
- an encoder that has a rotatable shaft;
- a control knob connected to said rotatable shaft;
- a control knob mounting protuberance that extends into the control knob and provides a bearing mounting surface; and
- a bearing mounted on the bearing mounting surface, said control knob having a hub portion extending through said bearing and engaging with the same so as to be rotationally supported therein, said hub portion further engaging with the rotatable shaft of the encoder;
- wherein the encoder is mounted within the assembly such that prior to attachment of the hub portion with the encoder shaft, the encoder is allowed a degree of movement whereby upon engagement of the hub portion with the encoder shaft, the encoder shaft comes into alignment with the hub portion.
2. An appliance control knob assembly according to claim 1, wherein said bearing is a rolling-element bearing comprising rolling elements rotatable within a circular race.
3. An appliance control knob assembly according to claim 2, wherein said bearing is a ball bearing comprising balls rotatable within said circular race.
4. An appliance control knob assembly according to claim 1, wherein the encoder is mounted on a printed circuit board (PCB) that is mounted within the assembly such that prior to attachment of the hub portion with the encoder shaft, the PCB is allowed a degree of movement, whereby upon engagement of the hub portion with the encoder shaft, the encoder shaft comes into alignment with the hub portion.
5. An appliance control knob assembly according to claim 4, wherein the PCB is mounted so as to be allowed a degree of movement in the plane of the PCB prior to said engagement of the hub portion with the encoder shaft.
6. An appliance control knob assembly according to claim 5, further comprising at least one holding element that presses against said PCB and thereby serves to hold it in place after an initial engagement of the hub portion with the encoder shaft.
7. An appliance control knob assembly according to claim 6, wherein said control knob mounting protuberance is provided on a front electronics enclosure housing, the assembly further comprising a rear electronics enclosure housing engaged with said front electronics enclosure housing, within which said encoder is mounted, said at least one holding element being mounted on said front electronics enclosure housing.
8. An appliance control knob assembly according to claim 1, wherein said bearing mounting surface is provided at least in part by a collar of the control knob mounting protuberance within which the bearing is secured.
9. An appliance control knob assembly according to claim 1, further comprising a chamfered surface provided on at least one of the encoder shaft and hub portion, that facilitates centering of the encoder shaft with the hub portion.
10. An appliance control knob assembly according to claim 4, further comprising a rear electronics enclosure housing, wherein the PCB is received within a cavity of said rear electronics enclosure housing, said cavity being larger than the PCB in at least one dimension to allow said degree of movement of the PCB.
11. An appliance control knob assembly according to claim 1, wherein the hub portion comprises a central bushing that is engaged with an inner race ring of the bearing to rotate therewith, said central bushing having a passage within which said encoder shaft is received.
12. A control knob assembly method comprising:
- mounting a bearing on a bearing mounting surface of a control knob mounting protuberance;
- mounting a control knob on said control knob mounting protuberance such that the protuberance extends into the control knob and a hub portion of said control knob extends through said bearing;
- movably mounting an encoder within a support structure of a control panel assembly, said encoder having a rotatable shaft; and
- engaging the hub portion with the encoder shaft such that the engagement is able to move the encoder within said support structure to thereby center the shaft with the hub portion in the event of a misalignment of the shaft and hub portion.
13. The control knob assembly method of claim 12, wherein the mounting of said encoder includes mounting a printed circuit board (PCB) with said encoder mounted thereon within said support structure.
14. The control knob assembly method of claim 13, wherein said support structure comprises a rear housing of the control panel assembly, said rear housing having a cavity that is larger than the PCB in at least one dimension to thereby allow a degree of movement of the PCB prior to said engaging of the hub portion with the encoder shaft.
15. The control knob assembly method of claim 14, further including engaging holding elements with said PCB after an initial engagement of said hub portion with said encoder shaft.
16. The control knob assembly method of claim 15, wherein said holding elements are mounted on a front housing of the control panel assembly, and said engaging of the holding elements with the PCB comprises engaging the front housing with said rear housing.
17. The control knob assembly method of claim 16, further comprising pre-assembling said control knob and bearing on said protuberance, which is provided as a part of said front housing, prior to engaging said front housing with said rear housing.
18. The control knob assembly method of claim 12, wherein said mounting of said bearing comprises fixedly attaching said bearing in a collar provided by said mounting protuberance.
19. The control knob assembly method of claim 16, wherein said mounting of said control knob comprises fixedly mounting said hub portion within an inner ring/race of said bearing.
20. The control knob assembly method of claim 12 wherein said bearing comprises rolling elements.
Type: Application
Filed: Nov 13, 2012
Publication Date: May 15, 2014
Patent Grant number: 9006591
Applicant: ELECTROLUX HOME PRODUCTS, INC. (Charlotte, NC)
Inventors: Mark David WILLIAMSON (Ames, IA), Chris H. HILL (Ames, IA)
Application Number: 13/675,315
International Classification: H01H 19/02 (20060101); H01H 11/00 (20060101);